This is a grant which contains a number of projects directed toward various aspects of the problems of sudden cardiac death and onset of myocardial infarction. The overall objectives include the development, application and evaluation of methods for earlier detection and therapy of individuals at risk for developing myocardial infarction and sudden death. Survivors of out-of-hospital ventricular fibrillation (3l7) who are known to be at high risk for recurrence of sudden death, are being intensively studied to determine the incidence and types of arrhythmias that can be detected by ambulatory monitoring and induced by exercise stress. The presence and types of arrhythmias and incidence of recurrence of sudden death in these subjects is being related to results of exercise stress testing, coronary anatomy and ventricular performance determined by angiography and myocardial perfusion determined by radionuclide techniques. Over 9200 subjects are being followed and data analyzed to determine the predictive value of the results of exercise stress testing and clinical evaluation. The prognostic significance of coronary anatomy, ventricular performance and exercise stress testing results with respect to development of sudden death and myocardial infarction is being evaluated. The effects of drug therapy and vein bypass graft surgery (1900 subjects) in prevention of sudden death and myocardial infarction is being assessed. One unit is determining the pathologic changes in the heart associated with sudden death.